head to head
Neither is simply harder - they are hard in different places. Portal 2 demands more execution; Sim Theme Park demands more variance.

Optimization · Pure Optimization
A first-person puzzle game where seeing the solution is the whole skill.

Optimization · Pure Optimization
Balancing park layout, pricing and staffing economics against predictable visitor demand.
Portal 2 leans Optimization (Pure Optimization); Sim Theme Park leans Optimization (Pure Optimization).
Portal 2 leans clearly harder on execution.
Portal 2
Portal placement requires some precision but timing is lenient.
Sim Theme Park
Menu-driven park management needs no dexterity
Same score on reads - which means the number cannot separate them. The difference is in what each one asks of you.
Portal 2
No opponent; puzzles are static.
Sim Theme Park
Visitor sims follow fixed demand rules
Sim Theme Park leans clearly harder on variance.
Portal 2
Puzzles are deterministic with no randomness.
Sim Theme Park
Guest desires are mappable after a park or two
Portal 2 leans clearly harder on optimization.
Portal 2
Solving the puzzle's logic IS the entire game.
Sim Theme Park
Layout, pricing and staffing math is the entire game
A matching score does not mean a matching test. Two games can both sit at 10 on execution and demand completely different things of you - which is why the reasoning above matters more than the number beside it.